MOBILE, Alabama -- The stepmother of Natalie and Chase DeBlase said she noticed a toxic smell on the children’s breath and saw them throwing up black vomit shortly before they died, and she believes they were poisoned by their father, according to police testimony today.

But the children’s father, John DeBlase, gave police a different account of what happened to the 4-year-old and 3-year-old siblings — tossing the blame on their stepmother, Heather Leavell-Keaton.

DeBlase told police that he found his children dead after his common-law wife stuffed the girl in a suitcase and tied the boy to a broomstick with duct tape and put a sock in his mouth, according to testimony.

The conflicting stories of how Natalie and Chase DeBlase died were recounted by the lead detective during a hearing in District Judge Charlie McKnight’s courtroom.

Police also said that at least a half-dozen witnesses saw the children suffer months of abuse, including daily beatings and starvation.

The children were reported missing, and possibly dead, on Nov. 18. They hadn’t been seen in months.

Investigators discovered Chase’s remains in a wooded area near Vancleave in coastal Mississippi on Dec. 8, and Natalie’s body was found near Citronelle in north Mobile County three days later.

DeBlase, 27, faces two counts of felony murder and two counts of abuse of a corpse. Leavell-Keaton, 22, faces two counts of aggravated child abuse and two counts of abuse of a corpse. This afternoon, prosecutors added two counts of capital murder against Leavell-Keaton.

Leavell-Keaton, who is legally blind, said she met John DeBlase on the Internet in October 2008, and several months later, they started living together with the children.

She said that DeBlase went to check on Natalie in her bedroom on March, but he emerged and said the girl was dead.

She said he also went into Chase’s bedroom for a while before telling her the boy was also dead in June.

Leavell-Keaton said she believed he poisoned them because she noticed they weren’t feeling well, had a toxic smell from their mouths and were vomiting.

The detective said that Leavell-Keaton admitted to riding along with DeBlase to get rid of their bodies.

Meanwhile, DeBlase was wanted for questioning and was detained in Escambia County, Fla., where he gave his version of what happened to the children.

At first, DeBlase claimed that on Father’s Day, the family was at a Mobile park when two unknown, masked gunmen kidnapped the children, according to the detective. He said he never called police “because he was scared for his children’s safety,” Prine said.

Moments later, he told police that the children died after suffering abuse at the hands of Leavell-Keaton.

He said that Natalie died in March after the stepmother put her in a suitcase, her limbs and mouth tied with duct tape, for more than eight hours. Her brother died in June after Leavell-Keaton tied him to a broomstick with duct tape, stuffed a sock in his mouth and left him in a corner overnight, he told police.

He said he bought a shovel at the Wal-Mart in Saraland on the way to getting rid of Natalie’s body in the Citronelle area, but the ground was too hard to dig a grave, according to the detective.

At Chase’s grave in Mississippi, the detective said, police found a sock and duct tape lying near his body.

Jim Sears, attorney for DeBlase, said the father is denying the charges against him “as he has from the very beginning.”

He declined to comment on whether DeBlase knew about all the abuse that’s been alleged in the case.

Several family friends later told police about daily abuse the children had to suffer from Leavell-Keaton, although none of the witnesses had previously reported it to authorities.

Prine said the witnesses described starvation, beatings with a studded belt, being called vulgar names, burns on their arms, bruises and a black-eye.

In one incident, a family friend said he saw DeBlase and Leavell-Keaton eat Wendy’s hamburgers while giving the two children only lettuce to eat, the detective testified.

One day, according to a witness, the stepmother beat the children after they’d snuck into a chocolate pie out of hunger.

Leavell-Keaton said she hated the children and called them “demon spawns from hell,” the detective said.

Darryl Bender, attorney for Leavell-Keaton, said the abuse allegations are not true, and the claims are being made by DeBlase’s friends.

“It is a very bad case and the facts that we heard today, if they are true, are bad,” Bender said. “But that’s sort of the question. Are they true? I think it’s clear to everyone who heard the testimony today who killed those kids. John DeBlase killed those kids.”

Assistant District Attorney Jo Beth Murphree said if prosecutors thought the witnesses were lying, “we would not have brought the charges.”

“We operate on the best information we have, and the best information we have indicates that these are the appropriate charges at this time,” Murphree said.

DeBlase is being held in jail on $506,000 in bail. Leavell-Keaton is being held on $206,000 bail.

At the end of the hearing, the judge ordered that the cases be considered by a grand jury. McKnight said that in 38 years, he’d never heard “a case of such acts.”

(Updated 3:25 p.m. to include further testimony from hearing and comments from attorneys.)